[tor-bugs] #18402 [Core Tor/Tor]: Reduce duplicate code in parse_*_time functions

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#18402: Reduce duplicate code in parse_*_time functions
-------------------------------------------------+-------------------------
 Reporter:  icanhasaccount                       |          Owner:
     Type:  enhancement                          |         Status:
                                                 |  needs_revision
 Priority:  Low                                  |      Milestone:  Tor:
                                                 |  0.2.???
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  unspecified
 Severity:  Minor                                |     Resolution:
 Keywords:  TorCoreTeam-postponed-201604,        |  Actual Points:
  nickm-deferred-20160905                        |
Parent ID:                                       |         Points:  1
 Reviewer:  yawning                              |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by teor):

 Replying to [comment:9 icanhasaccount]:
 > Hey all - I've had another look at this and its more complicated than I
 first thought.
 >
 > Looking at the 3 parse_*_time functions in util.c:
 >
 > parse_rfc1123_time: called from parse_http_response, or/directory.c
 > The result of parse_rfc1123_time isn't actually used anywhere in this
 function - could this be removed?

 parse_http_response is passed a date parameter, which is set to the result
 of parse_rfc1123_time. connection_dir_client_reached_eof uses it, but
 connection_read_https_proxy_response does not.

 > parse_http_time: called from directory_handle_command_get,
 /or/directory.c
 > if_modified_since always appears to be zero, so unless logging the
 failure result of parse_http_time is useful it seems this could be removed
 as well?

 if_modified_since is only set to zero if tor_timegm fails. Otherwise, its
 value is provided by tor_timegm. And it is used by
 directory_handle_command_get.

 > parse_iso_time_: called from rend_parse_v2_service_descriptor,
 or/routerparse.c and entry_guards_parse_state_for_guard_selection,
 or/entrynodes.c , both functions use the result of parse_is_time_ so this
 appears fine.

 And parse_iso_time_ (trailing underscore) is called by parse_iso_time (no
 trailing underscore), which is called by about 20 functions.

 > So before revising the diff I thought I'd check as a first step if
 parse_rfc1123_time and parse_http_time could (or should) be removed?

 No, they need to stay.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18402#comment:10>
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